Question

A box contains $90$ good and $10$ defective screws. If $10$ screws are selected at random the probability that none of them are defective

• A. $\frac{90}{100}$
• B. $1-\frac{90}{100}$
• C. $\frac{{90}_{C_{10}}}{{100}_{C_{10}}}$
• D. $1-\frac{{90}_{C_{10}}}{{100}_{C_{10}}}$

Answer 1

The correct option is C $\frac{{90}_{C_{10}}}{{100}_{C_{10}}}$

Probability of selecting $10$ of the $90$ good screws = $\frac{{}^{90}{C}_{10}}{{}^{100}{C}_{10}}$